Kilojoule is 1000 joule units.
Kilojoules to Watt-hours Converter — kJ to Wh
Convert Kilojoule (kJ) to Watt-hour (Wh) using the exact conversion factor (1 kilojoule = 0.2777777778 watt-hour). See the formula, worked examples, conversion table, and common uses.
Kilojoules to Watt-hours converter
Converter
Energy Converter
Convert joules, calories, kilowatt-hours, BTU, electronvolts, therms, and mechanical work units.
Context values
Some unit families need one extra value for a physically accurate result.
A watt-hour is 3,600 joules.
Result = input x 1000 / 3600.
Energy uses the joule as the base unit.
Reserved above the conversion cards and below the converter.
About Converting Kilojoules to Watt-hours
Kilojoule and Watt-hour both measure energy, and the conversion is especially useful for comparing nutrition labels (kilocalories) against scientific energy figures (joules). Specifically: Kilojoule is 1000 joule units, and a watt-hour is 3,600 joules.
Formula
watt-hours = kilojoules × 0.277777777778
This factor comes from each unit's defined relationship to the category's base unit: 1 kilojoule equals 1000 base units, and 1 watt-hour equals 3600 base units, so dividing one by the other gives the direct kilojoule-to-watt-hour factor of 0.277777777778.
Simple example
1 kJ × 0.2777777778 = 0.2777777778 Wh
1 kilojoule = 0.2777777778 watt-hours.
Real-world example
100 kJ × 0.2777777778 = 27.77777778 Wh
100 kilojoules = 27.77777778 watt-hours.
Conversion table
| Kilojoule (kJ) | Watt-hour (Wh) |
|---|---|
| 1 kJ | 0.2777777778 Wh |
| 10 kJ | 2.777777778 Wh |
| 100 kJ | 27.77777778 Wh |
| 500 kJ | 138.8888889 Wh |
| 1,000 kJ | 277.7777778 Wh |
| 2,000 kJ | 555.5555556 Wh |
Reverse conversion: Watt-hour to Kilojoule
0.2777777778 Wh × 3.6 = 1 kJ
0.2777777778 watt-hours = 1 kilojoules.
kilojoules = watt-hours × 3.6
For a page dedicated to this direction, see Watt-hour to Kilojoule.
Understanding the Kilojoule (kJ)
Kilojoule is 1000 joule units.
Understanding the Watt-hour
Watt-hour (Wh) measures energy. The energy delivered by one watt of power sustained for one hour — equal to 3,600 joules. It is classified as a metric derived energy unit.
Where it's used: Universal — standard consumer-electronics and battery energy unit worldwide
Wh vs. kWh. The same unit at different scales: 1,000 Wh equals 1 kWh. Wh suits small consumer-electronics batteries; kWh is used for household electricity billing and larger energy storage.
Uses of the Watt-hour today
- Phone, laptop, and power-bank battery capacity ratings
- Electric-vehicle battery capacity specifications
- Small-scale renewable energy (solar panel) output ratings
Watt-hour — sources
- BIPM SI Brochure — Watt-hour as a common energy unit derived from the coherent SI units watt and second (via the hour).
Reserved between the cards and the FAQ so the page stays balanced.
Frequently asked questions
How many watt-hours are in 1 kilojoule?
1 kilojoule equals 0.2777777778 watt-hours, using the exact defined conversion factor rather than an estimate.
How do I convert kilojoule to watt-hour?
Multiply the kilojoule value by 0.2777777778. The converter above does this instantly to whatever precision you set.
How do I convert watt-hour back to kilojoule?
Use the reverse factor: 1 watt-hour equals 3.6 kilojoules. You can also use the swap control in the converter above to flip the direction instantly.
What is a kilojoule?
Kilojoule (kJ) is a unit of energy.
What is a watt-hour?
Watt-hour (Wh) measures energy. The energy delivered by one watt of power sustained for one hour — equal to 3,600 joules. It is classified as a metric derived energy unit.
Is the kilojoule to watt-hour conversion exact?
Yes. Both kilojoule and watt-hour are defined by fixed standards rather than physical artifacts, so the factor of 0.2777777778 used above is exact to as many digits as you choose to display.
What is the difference between wh vs. kwh?
The same unit at different scales: 1,000 Wh equals 1 kWh. Wh suits small consumer-electronics batteries; kWh is used for household electricity billing and larger energy storage.